Mufflers used for silencing the exhaust from internal combustion engines in marine applications are known in the art and typically comprise a housing into which the exhaust gasses from the engine and sea water are routed. The muffler is typically connected to the transom of the watercraft or boat and the muffler outlet is routed above the water surface to avoid back pressure. The muffler housing has an internal construction designed to facilitate the passage of the exhaust gas therethrough while also deadening the sound waves of the exhaust gas to reduce the sound of the exhaust gas exiting the muffler outlet.
Conventional mufflers are designed to reduce the sound of the exhaust gas passing therethrough by either absorbing a portion of the sound waves, or by destructing the sound waves by reflection or expansion. Mufflers that are designed to attenuate the exhaust sound typically comprise a packing formed of an absorptive material or the like through which the exhaust gas is routed. Mufflers that are designed to destruct the sound waves by reflection or expansion typically comprise an arrangement of interconnected expansion chambers or a series of baffles position within the path of the exhaust gas. In either case, the use of such techniques whether effective or not adversely impacts the performance of the engine by increasing the air flow resistance or backpressure through the muffler. Routing the exhaust gas through the tortious path of chambers and/or baffles, or through an absorptive packing, increases the resistance of gas flow through the muffler, thereby restricting the free flow of exhaust gas from the engine and ultimately decreasing engine horsepower and performance.
It is, therefore, desired that a muffler be constructed that is capable of reducing the sound level of exhaust gas passing therethrough without increasing airflow resistance through the muffler, when compared with conventional mufflers. It is also desired that the muffler be constructed in a manner, and from a suitable material, to enable its use with internal combustion engines in a marine environment, e.g., with inboard-powered boats and watercraft, and the like.